I had tried another file you had for RSX
https://pdp-11.online/~form/files/pdp-11/rsx/basic-11/bas11v201.dsk
and it did not work for me. I tried not only mounting it files-11 under VCP but also used
FLX to see if it was
RT-11 or DOS-11 format. When you get a chance, would you take a look at it?
This is FILES-11 (ODS-1) disk image of BASIC-11 for RSX (y2k patched).
It's also available via HECnet at CTAKAH::SW:[KITS]BAS11V201.DSK